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Recently we proposed that the information contained in spontaneously emerging (resting-state) fluctuations may reflect individually unique neuro-cognitive traits. One prediction of this conjecture, termed the "spontaneous trait reactivation" (STR) hypothesis, is that resting-state activity patterns could be diagnostic of unique personalities, talents and life-styles of individuals. Long-term meditators could provide a unique experimental group to test this hypothesis. Using fMRI we found that, during resting-state, the amplitude of spontaneous fluctuations in long-term mindfulness meditation (MM) practitioners was enhanced in the visual cortex and significantly reduced in the DMN compared to naïve controls. Importantly, during a visual recognition memory task, the MM group showed heightened visual cortex responsivity, concomitant with weaker negative responses in Default Mode Network (DMN) areas. This effect was also reflected in the behavioral performance, where MM practitioners performed significantly faster than the control group. Thus, our results uncover opposite changes in the visual and default mode systems in long-term meditators which are revealed during both rest and task. The results support the STR hypothesis and extend it to the domain of local changes in the magnitude of the spontaneous fluctuations.

Amblyopia is a visual disorder starting at early childhood and characterized by reduced visual acuity not of optical origin or due to any eye disease. One expression of such an anomalous early visual experience is abnormal foveal vision. In a previous fMRI study, faces that were presented to amblyopic eyes evoked little response compared to houses in high-order visual areas. Patients also demonstrated reduced recognition of facial expression, raising the possibility that these face-selective abnormalities are related to foveal vision deficit. Whether this deficit originates in low-level processing or is mediated by compromised activation in high-order visual areas is unresolved. In the present functional magnetic resonance imaging (fMRI) study, we explored the impact of amblyopia on the representation of object images presented in foveally biased central versus peripheral retinotopic eccentricities through manipulation of object size. Small and large pictures were correlated to visual acuities of 6/6 and 6/60, respectively. In low-level visual areas, the amblyopic eye showed significantly reduced activation for centrally placed, small pictures than the sound eye, while activation to large pictures was only slightly reduced. Similarly, in high-order visual areas, the amblyopic eye showed marked reduction in activation in the fusiform gyrus, with normal activation in the collateral sulcus. The center/periphery size-related amblyopic outcomes of this study support a “bottom–up” nature of the center–periphery effect observed in high-order visual areas. Taken together, these findings point to the regional extent and functional selectivity of fovea-related cortical reorganization that is related to abnormal visual development of one eye.

Object completion is an inherent property of visual recognition in which objects can be accurately perceived in the presence of substantial obstructions. We have previously shown [Cereb. Cortex 12 (2002) 163] that high-order human object areas are driven partially by local object fragments and partially by global completion effects. Here we explored, through a backward masking paradigm, whether the balance of local and global processing is time dependent, that is, to what extent completion effects evolve at a different time compared to local image representations. In two separate experiments, subjects were presented with three types of images: (a) unobstructed line drawings of animal shapes ("whole"), (b) the same shapes obstructed by a set of parallel stripes ("grid"), and (c) a scrambled version of b in which the stripe position was shifted horizontally, disrupting the relative position of image regions but maintaining the local feature distribution ("scrambled"). Images were presented either for 60 or 250 ms followed by a mask. Both behavioral and fMRI findings from high-order occipitotemporal object areas showed consistently that object selectivity emerges at the same time as the local feature representation. Thus, object completion effects were evident at the same relative magnitude (LO: 0.5 +/- 0.3 and 0.58 +/- 0.04; pFs: 0.62 +/- 0.3 and 0.6 +/- 0.04; 60 and 250 ms, respectively) even at the short presentation durations when overall object activation was greatly reduced.